Personally,
I believe water wits should have a support/tank pet for Questing.. Like an example would be Angela, Elin, or Kanako... You're Earth wit can have any pet you want due to the fact that it is easy to train pets on an earth. Im not really good with deciding a pet for fire killer's since I usually dont use them. However, for a fire wit a favourite was always been Roca, Fred, Vic, Sam... Imo I prefer having a meelee pet for fire mage, or a support pet. Do not get a niss unless you are willing to lethe it at lvl 20 or feed it.
I believe this is the case for questing characters.
Hope this helped!